On the origin of strong photon antibunching in weakly nonlinear photonic molecules

TL;DR

This paper explains the quantum interference mechanism behind strong photon antibunching in weakly nonlinear photonic molecules, providing analytical insights and discussing potential applications in correlated photonic systems.

Contribution

It analytically identifies the quantum interference effect responsible for photon blockade in weakly nonlinear coupled cavities, advancing understanding of photon antibunching phenomena.

Findings

Quantum interference causes photon antibunching in weakly nonlinear systems.

Analytical expressions for optimal nonlinearity and detuning are derived.

Limitations and applications in correlated photonic arrays are discussed.

Abstract

In a recent work [T. C. H. Liew and V. Savona, Phys. Rev. Lett. {\bf104}, 183601 (2010)] it was numerically shown that in a photonic 'molecule' consisting of two coupled cavities, near-resonant coherent excitation could give rise to strong photon antibunching with a surprisingly weak nonlinearity. Here, we show that a subtle quantum interference effect is responsible for the predicted efficient photon blockade effect. We analytically determine the optimal on-site nonlinearity and frequency detuning between the pump field and the cavity mode. We also highlight the limitations of the proposal and its potential applications in demonstration of strongly correlated photonic systems in arrays of weakly nonlinear cavities.